Date Format Error in swift

Question

I am new to the swift library. I am using the calendar in swift and I want to show the events in calendar. The events are obtained from the Json API but when I compare the date it is showing an error.

This is the code

  let data = event["date"] as? String
  let newString = data?.replacingOccurrences(of: "/", with: "-")
  self.FirstData = self.EventDates[0]

compare function

 func compareDate(date : String){
        let date = date

        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
      ====>>>>Error in line 
  let dateFromString : NSDate = dateFormatter.date(from: date)! as NSDate 
        dateFormatter.dateFormat = "yyyy-MM-dd"
        let datenew = dateFormatter.string(from: dateFromString as Date)
        print("datee",datenew)

    }

Error: fatal error: unexpectedly found nil while unwrapping an Optional value

How to compare date or resolve this issue.

Check the date which you are passing in `compareDate`. It should be of format `yyyy-MM-dd'T'HH:mm:ss` — Aditya Srivastava, Aug 24 '17 at 11:05
Why the casting to `NSDate`? And either your dateformat is wrong or you need to set up the `Locale` of the `DateFormatter`. — Dávid Pásztor, Aug 24 '17 at 11:05
Possible duplicate of [how to compare date in swift 3.0?](https://stackoverflow.com/questions/42294529/how-to-compare-date-in-swift-3-0) — Mateusz, Aug 24 '17 at 11:07
`"11-23-2016"` clearly is not formatted as `yyyy-MM-dd'T'HH:mm:ss`, therefore date formatter returns `nil`, and when you force unwrap it with `!` you get a crash. — user28434'mstep, Aug 24 '17 at 11:19
Why do you convert the string with `replacingOccurrencesOf`? `DateFormatter` can handle slashes, too. And do not use `NSDate` in Swift 3. — vadian, Aug 24 '17 at 11:21

score 2 · Answer 1 · answered Aug 24 '17 at 11:11

try this :-

func convertDate(date:String) -> String {
     let dateFormatter = DateFormatter()
    let tempLocale = dateFormatter.locale // save locale temporarily
    dateFormatter.locale = Locale(identifier: "en_US_POSIX") 
   // date format getting from server 
     dateFormatter.dateFormat = "YYYY-MM-dd'T'HH:mm:ss.SSSSSS'Z'"

    let date = dateFormatter.date(from: date)!
    //date format you want
    dateFormatter.dateFormat = "yyyy-MM-dd"
    dateFormatter.locale = tempLocale // reset the locale
    let dateString = dateFormatter.string(from: date)
    print("EXACT_DATE : \(dateString)")
    return dateString
 }

score 1 · Answer 2 · answered Aug 24 '17 at 11:12

date(from:) returns an optional Date simply because it may fail to properly convert the given string. As you cannot be sure when this happens you must not force unwrap the result (dateFormatter.date(from: date)!) but rather safely unwrap the optional, i. e. using this construct:

if let dateFromString: NSDate = dateFormatter.date(from: date) as NSDate {
    ...
}

score 0 · Answer 3 · answered Aug 24 '17 at 11:11

0

try this to change date format

 let dateFormatter = NSDateFormatter()
 dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
 dateFormatter.timeZone = NSTimeZone(name: "GMT")
 let date = dateFormatter.dateFromString("2012-12-06 T 06:00:00 ")

 dateFormatter.dateFormat = "yyyy-MM-dd"
 let goodDate = dateFormatter.stringFromDate(date!)

answered Aug 24 '17 at 11:11

Vikas Rajput

1,754
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bro I can run this code let goodDate = dateFormatter.string(from: date!) getting error – Dhruv Aug 24 '17 at 11:20
1

Why use `Foundation` classes when they have native Swift equivalents (`DateFormatter` and `TimeZone`)? – Dávid Pásztor Aug 24 '17 at 12:15

MinuMaster · Accepted Answer · 2017-08-24T11:30:16.990

0

Your app is crashing because of date string was not in the same format which was assigned to dateformatter. Because of that date object return nil value.

And you force nil value to convert NSDate object. Because of that app is crashing.

You just need to change your compare date method as below:

func compareDate(date : String) -> Date? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "MM-dd-yyyy"
    let dateFromString = dateFormatter.date(from: date)
    print("datee", dateFromString ?? "")
    return dateFromString
}

By doing this you can able to create the Date object.

edited Aug 24 '17 at 11:30

answered Aug 24 '17 at 11:13

MinuMaster

1,457
1
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@Dhruv try this code it will work for creating date object as you received date in "11-23-2016" format. – MinuMaster Aug 24 '17 at 11:16
Why did you kept those `Date -> NSDate -> Date` nonsense casting? Just get rid of it. – user28434'mstep Aug 24 '17 at 11:21
https://stackoverflow.com/questions/45261579/how-to-compare-json-api-dates-with-fscalendar-and-display-events-in-tableview?rq=1 am trying to do like this – Dhruv Aug 24 '17 at 11:30

Date Format Error in swift

4 Answers4